Anode Materials for Lithium-Ion Capacitors: From Fundamental Mechanisms to Design Strategies

Abstract

Lithium-ion capacitors (LICs), which integrate battery-type anodes with supercapacitor-type cathodes, have emerged as promising energy storage devices by bridging the high energy density of batteries with the high power density of supercapacitors. However, their practical deployment remains hindered by inherent limitations in anode materials, particularly sluggish ion diffusion capability and inherent instability, which degrade energy efficiency and cycling stability under high-rate operation. This review critically examines the fundamental challenges and recent advancements in LIC anode engineering. We present a pioneering analysis of key performance bottlenecks, including kinetic and thermodynamic incompatibilities between Faradaic (battery-type) and capacitive charge storage mechanisms, with a focus on strategies to address sluggish charge/mass transport and structural/interface degradation. A systematic comparison of insertion-type, conversion-type, and alloy-type anodes, alongside emerging material candidates, elucidates how structural design, surface/interface modifications, and composite hybridization synergistically improve ion transport kinetics while mitigating mechanical degradation. Furthermore, we discuss critical challenges in designing next-generation LICs and highlight innovative tools to optimize energy-power trade-offs. By linking atomic-level material design to macroscopic device performance, this work outlines a roadmap for developing advanced LICs capable of meeting stringent grid-scale storage demands and accelerating the adoption of sustainable energy systems.